1. Field of the Invention
The present invention pertains to conductive substrates applicable to recording processes, and more particularly, to conductive substrates for which the conductive layer thereof exhibits enduring conductive characteristics and excellent resistance to water.
2. Prior Art
Conductive substrates are conventionally used for supporting the image recording layer in electrostatic recording media, photosensitive media used for electrophotography, and other types of printing and copying media.
Electrostatic copying and printing methods which employ media incorporating a conductive substrate and devices which employ such methods have enjoyed widespread popularity, including facsimile devices, printing and reproduction devices for mechanical drawings, schematic diagrams, etc., devices for printing proofsheets for use in proofreading for newspapers and other publications, and devices for copying official documents and the like. Furthermore, in recent years, refinements in electrostatic copying and printing methods have made production of multicolor copies and prints possible, which has been put to use for diverse applications including the field of design in general, as well as for production of advertisement and promotional fliers, programs for plays, sporting events and the like, and various other applications.
As a consequence of the growing popularity of electrostatic recording and copying methods, there is an intense demand for media applicable to such applications, which can be used for outdoor applications, and which therefore is capable of withstanding exposure to water and other environmental factors, while retaining a legible and attractive image despite such exposure. Unfortunately, in comparison with the rapid progress seen for electrostatic printing technology in general, development of electrostatic recording media which faithfully retain an image or text imparted thereto for an extended period of time, and which demonstrate enhanced resistance to material and image deterioration due to exposure to water and other environmental factors has lagged significantly behind.
In response to the need for water resistant electrostatic recording media, various attempts to provide therefor have been made, for example, by applying a conductive layer over a substrate made of paper, resin film, cloth and the like which has been previously treated so as to impart water resistance thereto, where the conductive layer is one such as that disclosed in Japanese Patent Application, First Publication No. Sho-61-264345. In the above cited reference, for the conductive component of the conductive layer, a cationic high molecular weight electrolyte material containing amine group was used. For the electrostatic recording medium thus produced, the electrical resistance characteristics were found to be stable over a wide range of conditions, with little variation thereof resulting from changes in the relative humidity. Consequently, in terms of humidity dependent characteristics, the electrostatic recording medium prepared as described above was found to be satisfactory. Unfortunately, due to the fact that the employed electrolyte material containing amine group is water soluble, exposure to rain or moisture resulted in solublization thereof, with subsequent peeling of the conductive layer, and hence, of the electrostatically printed image. As a result, this electrostatic recording medium was found to be unsuitable for outdoor applications.
Thus, despite an ongoing effort to develop electrostatic recording media applicable to outdoor applications, it has not as yet been possible to produce such media, that ia, it has not yet been possible to produce electrostatic recording media which can faithfully retain an image or text imparted thereto over an extended period of time, and which demonstrate significant resistance to material and image deterioration due to exposure to water and other environmental factors.